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Tuesday, November 12, 2013

In my post yesterday on the potential loss of the last years of Cassini's extended mission at Saturn, I quoted the wrong costs for operating Cassini. The correct figure is $60-65M per year, and not the $50-55M. (The latter reflected a potential cut -- at the cost of a reduction in science conducted -- proposed for a past funding review.)The following link provides a lot of detail on the current extended mission (through the end of Fiscal Year 2014) and the science results: http://www.lpi.usra.edu/opag/mar2012/presentations/OPAG_Thurs_morning/5_Cassini_Status_Spilker.pdf

Update, August 2014. NASA has now committed to fully funding the Cassini mission to it's planned end in 2017.NASA’s shrinking budgets for
planetary exploration may force it to decide between continued funding for the
Saturn Cassini mission and the continued funding for its Mars missions. Mars would seem to be the likely winner. If so, we would lose a dramatic ending to the
Cassini mission that would be essentially an entirely new mission to Saturn. The ring and cloud-top grazing final orbits would
produce entirely new science and would be as rich as the Juno mission to
Jupiter.

Note: I've corrected this post to reflect Cassini extended mission costs of $60-65M per year instead of the $50-55M in the original post.

Comparison the possible end-of-mission orbits for Cassini and the orbits for Juno. By dipping close the rings and atmosphere, Cassini can make highly detailed measurements of the rings, atmosphere, and Saturn's interior. The Juno mission en route to Jupiter will provide similar measurements for Jupiter's atmosphere and interior. Source: NASA's Outer Planets Assessment Group (OPAG).

Operating planetary missions is an expensive proposition. This year, NASA will spend something like
$215M or ~18% of is planetary science budget operating its fleet planetary
spacecraft that have already launched.
(These numbers are approximate because NASA doesn’t separate out the
costs of operating the Cassini and Lunar Reconnaissance Orbiter missions.)

The initial costs of operating a mission during its early phases, what is
known as the prime mission, are included in the funding budgeted specifically
for the mission. Once a spacecraft
continues operating past its prime mission (most do), it enters what is known
as an extended mission. NASA budgets
money to operate extended missions. The amount
planned for the next several years is fixed and doesn’t go up with the number
of extended missions. As a result,
there’s a process known as the Senior
Review that judges which missions should continue to be funded and at what
levels to divvy up the pie.

For the past several months, NASA
has been warning the planetary community that there will be insufficient
funds to operate its all extended missions at their current levels.

The Senior Review encourages mission teams to both be clear on what new
science is enabled and to find ways to continue to operate on smaller budgets
than were used for operations in the prime mission. It’s not unusual for the science return in an
extended mission to equal or exceed that of the preceding prime mission.

In general, mission teams use three key justifications for
funding extended missions:

In the prime mission, it’s not unusual for new
discoveries (e.g., the plumes of Enceladus) to be made, but scientists aren’t
sure what they mean or what processes drive them.Those discoveries become the subject of
follow up observations (e.g., multiple passes through the plumes to conduct a
variety of targeted measurements) that greatly deepen our understanding.

Many processes simply require a long period of
time to observe.For example, the Mars
Reconnaissance Obiter has imaged and re-imaged many seemingly blank spots on
the surface of Mars.At some of those
spots, small meteor strikes revealed ice lying just below the surface.The ice later sublimated away; only repeat
imaging revealed the ice during the brief time it was visible.

An extended mission may allow the spacecraft to move
to a new location for entirely new observations.The extended mission of the Opportunity rover
has allowed it to essentially become a “new” mission at least twice by arriving
at locations that were considerably different than those visited in the prime
mission.In another example, the lunar
GRAIL orbiters used their extended mission to map the moon’s gravity field from
a much lower (and riskier) orbit than the orbits of the prime mission,
resulting in higher resolution maps.

The budget problem for NASA is that the demand for extended mission
funding will jump in FY15 when Curiosity begins its extended mission. At best, NASA’s budget for extended missions
will be flat (news accounts quoting NASA managers) or be cut by eliminating
funding for Cassini mission operations.
(The latter is suggested by NASA’s budget documents which show the
budget that funds Cassini dropping to levels that don’t support the extended
mission.)

Demand up, budget flat or down, something may have to go.

The Senior Review will look across all missions and could recommend
funding Cassini instead of one or more Mars missions. However, that seems unlikely to me. The Curiosity mission is just beginning what
is likely to be a decade of exploration.
The Mars Reconnaissance orbiter is required to help select landing sites
and travel routes for the planned 2020 Mars rover as well as relay data from
the rovers. The Mars Odyssey orbiter is an essential data relay for
currently operating rovers. And who
would suggest turning off the venerable Opportunity rover? (Neither of the last options provides much in
the way of savings anyway; they are lean, mean extended missions.)

Cassini has had a long run at Saturn, having entered orbit in 2004 and
been operated as an extended mission after the first four years. Between the end of its current extended
mission in late 2014 and the time the spacecraft is expected to run out of fuel
in 2017, the spacecraft could continue to follow up on past discoveries (for
example, with three final Enceladus flybys).
It also would continue to look for seasonal changes at Titan and
Saturn.

However, in its last year of possible operation before its fuel is
exhausted (November 2016 to September 2017), Cassini could become an entirely
new mission.

Up until November 2016, Cassini will have stayed well away from
Saturn’s rings (except during orbit insertion in 2004) because the risk of
catastrophic collision with an ice particle or boulder would be too high. With the fuel almost exhausted, though, Cassini’s
managers want to bring it in close to the rings and Saturn itself. Twenty orbits would carry the spacecraft just
outside the rings for close up observations of their structure and mass. (The latter measurements, for example, would
help scientists determine how old the rings are.)

Following these orbits, the spacecraft would slip into the gap between
the inner most ring and the top of Saturn’s atmosphere. From these 22 close-in orbits, the Cassini
mission would essentially replicate the measurements that will be made at the
same time by the Juno mission to Jupiter:
detailed measurements of the interior of Saturn and of its
atmosphere. As a bonus, scientists can
make more detailed measurements of the rings.
And for all of us who vicariously explore the solar system through these
missions, think of how beautiful the images would be looking out at the rings
and Saturn from just above the clouds.

At the end of the mission, its fuel gone, Cassini would enter and burn
up in Saturn’s atmosphere, an end that would prevent it from accidently
impacting and contaminating Enceladus or Titan with micro-organisms from Earth.

All of the science in this end-of-mission scheme would be new, never done
before science because extending the mission would allow Cassini to go to
somewhere new. NASA thought that these measurements were so
valuable at Jupiter that they funded and are flying the ~$1B Juno mission,
which will do similar science there.

At one time, funding for Cassini’s full extended mission to the end of
2017 had been approved. Then NASA’s
planetary budget was cut and now the mission has to seek approval again to
continue operating.

I suspect that the Cassini team is scrubbing its budgets to look for
ways to reduce costs and still enable the close up orbits at the end of the
mission. That team has stated before,
though, at a large portion of the budget goes to simply operating the
spacecraft safely. Cuts would have to
come from reducing science operations. (I
don’t know if the orbital ballet enabling the close-in orbits would allow them
to be done earlier to shorten the length of the extended mission.)

However, the real solution is
for NASA to receive more funding so that it doesn’t have to make choices that
turn off a highly productive mission to save 4% of its planetary science budget.

If you would like to see Cassini make those final orbits, skimming the
rings and Saturn’s atmosphere, I encourage you to join
the Planetary Society’s campaign to have NASA’s budgeting program receive
more funding.

Appendix: Budgets for extended missions

For those who like to see the numbers, I’ve gone through NASA’s Fiscal
Year 2014 budget proposal to pull out the planned budget for extended missions
and the budget for Curiosity’s last year of funding in its prime mission.

The budget doesn’t break out funding for the Cassini or Lunar
Reconnaissance orbiter. Public accounts
have put the Cassini extended mission operations at $60M to $65M a year. The MESSENGER orbiter at Mercury is expected
to run out of fuel before the start of FY15, and will not be needing funds
beyond FY14.

All extended missions currently are funded through the end of
FY14. The crunch begins in FY15 when the
budget numbers show a funding cut and Curiosity needs new funding to begin its
extended mission.

FY14

FY15

Cassini

$50.0

Saturn

Curiosity

47.1*

Mars

Mars extended missions

$82.3

Mars

Mars Reconnaissance
Orbiter

$30.5

Mars

Opportunity

$14.7

Mars

Mars Odyssey

$12.8

Mars

Messenger

$4.9

Mercury

Mars Express

$2.2

Mars

Lunar Reconnaisance
Orbiter

?

?

Moon

Extended Missions

$115.1

$82.3

* Prime mission funding

Funding identified in NASA FY14 budget
proposal for extended missions

While NASA’s budget documents don’t show spending categories within the Outer Planets budget category, the chart
below shows sharp cuts to this account.
By FY16, funding is too low to support the Cassini mission (and may represent
NASA’s contribution to Europe’s JUICE Jupiter/Ganymede mission). There
may be some funding for Cassini in FY15.
Proposed budgets following FY16 show approximately flat funding.

Wednesday, November 6, 2013

In September
I wrote about the European Space Agency’s competition to select its next
two large (~€1B) science missions. While
many exciting solar system concepts were included, ESA’s management selected
X-ray and gravity observatories as its missions to fly in 2028 and 2034. Both missions promise to deepen our knowledge
of the universe considerably. (The journal
Nature has a good overview of the missions.)

While it’s disappointing the ESA did not select a planetary mission,
Europe will make strong contributions to planetary exploration in the next two
decades with the Rosetta mission rendezvousing with a comet (2014), a Mars
orbiter (2016), a Mars rover (2018), the Bepi-Colombo Mercury orbiter
(arrives 2022), and the JUICE Jupiter
and Ganymede orbiter (arrives 2030). This
is in addition to the currently operating Venus and Mars Express orbiters.

Europe can still select planetary missions for its Medium-scale
program. The Marco Polo-R asteroid
sample return mission is currently in consideration for the next
selection. ESA’s Mars program is also
funded separately and is looking at missions for the 2020s.

About Me

You can contact me at futureplanets1@gmail.com with any questions or comments.
I have followed planetary exploration since I opened my newspaper in 1976 and saw the first photo from the surface of Mars. The challenges of conceiving and designing planetary missions has always fascinated me. I don't have any formal tie to NASA or planetary exploration (although I use data from NASA's Earth science missions in my professional work as an ecologist).
Corrections and additions always welcome.